Automatic timing device



Jan. 11, 1949. w. H. MITSCH AUTOMATIC TIMING DEVICE 3 Sheets-Sheet 1Filed Feb. 9, 1946 QLZM M William H. Miksch,

Patented Jan. 11, 1949 UNITED STATES PATENT OFFICE AUTOMATIC TIMINGDEVICE William H. Mitsch, Wheeling, W. Va,

Application February 9, 1946, Serial No. 646,674

This invention appertains to automatic timing devices generally, andmore particularly to one which, while being capable of use as a sequencetimer for any machine or process, is especially adapted to theoperational control of resistance welding machines employing airpressure for applying the electrodes to the work.

At present, sequence timers are manufactured in a variety of forms, mostof which depend for their operation upon the charge and discharge ofcapacitors in electronic tube circuits and wherein a condenser ischarged through a resistor and, at a predetermined voltage, theelectronic tube conducts enough current to operate a relay. Hence, byinterconnecting a number of such circuits, a sequence of operations iscontrolled. Another form of sequence timer, to produce a variable timedelay, employs filtered air which is forced through a graduatedadjustable orifice, so that, by employing a number of such units, asequence of operations can be controlled. Motor driven sequence timersare also well known but operate with the disadvantage that one timeperiod cannot be changed without altering the I speed, or changing theother time periods.

However, in the instant invention, it is an object to make use of themagnetic flux of an expanding or collapsible field to obtain the desiredtime period and, to such end, four time-delay relays, operating on thisprinciple, are employed to control a resistance welding machine of thespot or projection type, in the operation of which, four periods of timeare required, the same being commonly known as squeeze, weld," hold, andoil.

Another object of the invention has to do with providing each of theaforesaid time-delay relays With a means of adjustment, so that, thetime periods in the operation thereof can be readily and easily variedwith precision to meet any of a Wide range of work requirements.

With the foregoing and other objects and advantages of equal importancein view, the invention resides in the certain new and usefulcombination, construction, and arrangement of parts and circuits, aswill be hereinafter more fully described, set forth in the appendedclaims, and illustrated in the accompanying drawings, in which:

Figure 1 is a side elevational view, partly in section, of a panelmounting for certain of the operational elements of the timing device,and showing diagrammatically the circuit connections between certain ofthe operational elements 2 Claims. (Cl. 171-97) iii 2 and the operatingparts of a welding machine, in accordance with the invention;

Figure 2 is a somewhat enlarged, fragmentary, section, taken on the line2-2 of Figure 1, lookin in the direction of the arrows;

Figure 3 is a diagrammatical view of the control circuits of the device;and,

Figure 4 is a diagrammatical view, showing the order of operation of theseveral relays for controlling the welding machine through two completecycles of its operation.

Referring to the drawings, and more particularly to Figures 1 and 2, thecontrol panel, as it is exemplified therein, is comprised in a mountingpanel l0, having an angled bracket l2, fastened horizontally on its rearside, to support four time-delay relays l5, i8, 20, and 22, in verticalposition and in line thereon; two of the relays at each side of arectifier tube l4, also supported on the bracket. The lower or heel endof the frame 24, of each of the relays, is fastened, by means of a screw26 (Figure 2), to the horizontal portion of the bracket !2, while theheel end of the core 28 is fastened, by means of a screw 30, to the likeend of the frame; the horizontal portion of the bracket being apertured,as at 32, to permit of access to the screw 30, without need to dismountthe relay from the bracket.

In order to adjust the time period of opera tion of each of the relaysl6, i8, 20, and 22, a collar 34, of copper or an alloy thereof, isslidably mounted on the core 28, between the heel ends of the frame 24and he relay coil, and it is formed with an arm 36 extending in spacedparallel relation to the core and downwardly through an opening 46,formed in the bracket l2. One side of the arm 36 is formed with a seriesof rack teeth 38, arranged in mesh with a gear 42, which is keyed on theinner end of a shaft 44, that has bearing in the secured portion of thebracket l2 and the mounting panel ID; the opposite end of the shaft 44,at the front side of the panel, being provided with a control knob 46.Mounted on the shaft 44, between the panel Ill and the knob 48, is anindex 48, having the form of a pointer which is turnable with the shaftand relatively to a graduated scale (not shown), delineated on the panelface. A guide roller 50 is mounted on a stud 52, fixed in the securedportion of the bracket 12, and has rotating contact with the arm 36, ata point thereon directly opposite to that of the gear 42, in order toaccurately guide the arm in its linear movements of adjustment, when theshaft 44 is turned valve that, in turn, controls the operation of themovable electrode of the welding machine, and

the relay 53, the operation of the contactor during the weld period ofthe latter. A control switch til, preferably of the push button type,is.

carried at the free ends of a pair of leads extending from a set ofcircuit terminals 62 on the panel iii, while A.-C. power line leads areconnected to a set of terminals 54, also on the panel, in circuit with asection S of the secondary winding,

S, of the transformer 56. The relay 56 is provided with a pair of fixedcontacts and a movable bridging contact iita, with the fixed contactsconnected to a pair of terminal posts 66, while the relay E3 is likewiseprovided with a pair of fixed contacts and a movable bridging contact53a, with its fixed contacts connected to a pair of terminal posts 38.One of the terminal posts tit is connected to one side of the solenoidalvalve coil 8t and the other terminal post to one side of the A.-C. powerline and one of the terminal posts 58, of the relay 58, while thesecond, of the latter is connected to one side of the solenoidalcontactor coil t6, which has its other side, along with the other sideof the solenoidal valve coil 5%, connected to the remaining side of thepower line.

The welding machine, as illustrated in Figure 1, is a conventional type,and includes a frame it, supporting a cylinder 12, housing a piston 74,which is connected to a movable electrode 62. The cylinder '52 isprovided with an inlet 16 for connection to a suitable source of fluidpressure (not shown), such as compressed air, for the actuation of thepiston M; a valve element 78 being mounted in the frame it? and adaptedto be actuated by a solenoidal coil 80. A fixed electrode 84 issupported by, but insulated from, the lower part of the frame ill, forcooperation with the movable electrode 82. Leads 90, from the electrodes82 and 84, are connected to thesecondary winding of the weldingtransformer T, the primary winding of which is connected to the powerline, with one of its leads severed for connection with the fixedcontacts of the welding circuit contactor, which contacts are adapted tobe bridged by a movable contact member 38, upon the energization of thesolenoidal coil 86 that occurs whenever the relay 58 is operated.

In the circuit arrangement shown in Figure 3, the contacts liia, ltd,and 20a, of the relays l6, l8, and 253, respectively, are normallyclosed, while all of the others thereof and of the remaining relays 22,56, and 5%, are open. With the A.-C. power line leads connected to theterminal posts 64, the supply voltage is applied to the primary windingP, of the transformer 54, and the filament cathode of the vacuum tube 14heats up; the energizing current for the filament cathode beingfurnished by the section S, of the secondary winding S of thetransformer 54, and the direct current for the electromagnetic windingsof the several relays It through 22, by the recti" fication of the A.-C.generated in the other sec tion. After the elapse of a few seconds, thetube M furnishes a direct current which immediately acts to energize thecoils of the relays l8 and 22, causing the contacts 22a and 22b to closeand the contacts 68a to open. By now closing the push button switch 58,the coil of the relay i6 is energized, causing the contacts ltb and lficto close and the contacts ifia to open; the contacts 5617, when closed,forming a holding circuit for the coil of the relay l6, and the contactsitc, causing the energization of the coil of the power control relay andtheclosing; of the contacts 55a; of the latter, on the solenoidal coililil for the operation of the compressed air valve 18 or the weldingmachine. With the closing of the contacts liib and ific, as aforesaid,the push button switch may be released to its normally open circuitedposition. With the opening of the contacts ita, of the relay it, thecoil of the relay i8 is de-energized and, after a delay, the contactslBa thereof closes; the delay, as before stated, being due to thetime-delay, or slow release, characteristics of the several relays it,58 2.3-, and 22. This delay interval constitutes the squeeze. period ofthe movable electrode 32 relatively to the fixed electrode 8t and thework interposed therebetween. With this closing of the contacts lSa, oithe relay is, the coil of the relay 28 is energized, causing thecontacts 28b to close on the coil of the power control relay 58, whichacts to close its contacts 58a on the solenoidal coil 86-, of thecontactor of the welding machine. With the activating of the solenoidalcoil 86, the contacts 88 close on the welding transformer, for

the application of the secondary current of the latter to the electrodes82 and 84. At this time,

' the contacts Zila, of the relay 2%, open to effect a de-energizing ofthe coil of the relay 22, and, after an interval of time, its contacts22a and 2212 open; the time delay interval here constituting the weldperiod of operation of the Welding machine. At the end of this delayperiod, the opening of the contacts 22b ole-energizes the coil of therelay 53, causing the contacts 58m to. open on the solenoidal coil 86and the contacts 3% on the welding transformer and the electrodes 82 rand 84. At the same time, the contacts 22a, of

the relay 22, open and cause the de-energization of the coil of therelay 5%. After a succeeding elapse in time, constituting the holdperiod. of operation of the welding machine, the contacts it'a close andthe contacts 5% and 460 open; the

contacts i ta closing the circuit on the coil of the relay it, while thecontacts itb breaks the circuit around the push button switch 69 and.the con,- tacts 56c cause the de-energization of the coil: of

the relay along with the solenoidal coil 810,

with the result of the return of thecompressed air valve E8. to, itsnormal position and the consequent separation of the movable electrode82 from the work. With the latter closing of the contacts iiitnoi therelay it, the coil of the relay i8 is energized, causing the contacts811. to openon the coil of the relay 26, the de-energizing of which,after a delay in time constituting theofi period in the weldingoperation, causes its con.- tacts 29a to close, thus restoring thetiming system to its original state, ready for a repeat op.- eration.

By reference to Figure 4, the sequential periods of inter-operation ofthe several relays l6, I8, 20', 22, 56, and 5B, is to be readilyvisualized through two cycles of welding machine operation, each cyclebeing performed in accordance with the above description. However, ifthe push button switch 66 is opened at the time indicated, all

further action of the timer will cease upon the completion of a singlecycle of welding machine operation, but, if the switch 60 is heldclosed, the sequential operation of the relays will be repeated for anygiven number of cycles thereof. Again, if the switch 60 is opened at anytime, after its initial closing to initiate the operation of the timingsystem, the operational sequence of the relays will continue to completethe welding cycle as before stated. Y

While in the foregoing I have described In invention in connection withan exemplary use thereof, it is to be understood that my timing systemmay be employed with any type of machine or process involving sequentialoperative steps other than as herein disclosed. Hence, while I havedescribed my invention in its preferred embodiment, it is also to beunderstood that the words which I have used are words of descriptionrather than of limitation, and that changes within the purview of theappended claims may be made without departing from the true scope andspirit of my invention in its broader aspects.

What I claim is:

1. An electric sequence timer system, comprising a D. C. controlcircuit, an A. C. power circuit, a transformer including a primarywinding connected in said power circuit and a secondary winding in saidcontrol circuit, a rectifier connected to and between said secondarywinding and said control circuit to supply D. C. to the latter, aplurality of electromagnetic relays connected in said control circuit, aplurality of electromagnetic switches connected in said power circuit,and a manually operated switch connected in said control circuit, one ofsaid relays having its winding connected in series with said switch anda pair of normally open contacts in series with said winding and shuntedabout said switch, a second of said relays having its winding connectedin said control circuit and in parallel with the winding and contacts ofsaid one relay and in series with a second pair of normally closedcontacts of the latter, said second relay having a pair of normallyclosed contacts connected in said control circuit and in parallel withits winding, a third of said relays having its winding connected in saidcontrol circuit and in parallel with the winding of said second relayand in series with the contacts of the latter, said third relay having apair of normally closed contacts connected in said control circuit andin parallel with its winding, a fourth of said relays having its windingconnected in said control circuit and in parallel with the winding ofsaid third relay and in series with the contacts of the latter, saidfourth relay having a third pair of normally open contacts connected insaid control circuit and in series with the winding of said one relay,said one relay having a third pair of normally open contacts connectedin said power circuit and in parallel with the primary winding of saidtransformer, one of said electromagnetic switches having its windingconnected in said power circuit in series with said third pair ofcontacts and having a pair of normally open contacts also connected insaid power circuit and in parallel with its winding and in series withthe winding of an electromagnetic device for the operative controlthereof, said third relay having a second pair of normally open contactsconnected in said power circuit and in parallel with the winding of saidone electromagnetic switch and in series with a second pair of normallyopen contacts of said i'ourth relay and the winding of a second oi saidelectromagnetic switches, said second electromagnetic switch having apair of normally open contacts connected in said power circuit and inparallel with its winding and in series with the winding of a thirdelectromagnetic switch, said one electromagnetic switch having a pair ofnormally open contacts connected in said power circuit and in parallelwith its winding, said third electromagnetic switch having a pair ofnormally open contacts connected in said power circuit and in parallelwith its winding and in series with the primary winding of an outputtransformer, whereby, upon the momentary closing of said manuallyoperated switch, the windings of said relays and said electromagneticswitches will be sequentially energized to perform their respectivefunctions through a single cycle of operation.

2. The invention as defined in claim 1, with each of saidelectromagnetic relays of a delayed action type and provided with meansfor the adjustment of the time delay period of operation thereof.

WILLIAM H. MITSCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,742,367 Nettleton Jan. 7, 19301,922,089 Hovey Aug. 15, 1933 1,969,064 Field Aug. 7, 1934 2,092,021Richterkessing Sep. 7, 1937 2,118,424 Watanabe May 24, 1938 2,123,063Peters July 5, 1938 2,124,795 Roby July 26, 1938 2,140,576 Fisher Dec.20, 1938 2,179,957 Roby Nov. 14, 1939 2,277,579 Burger Mar. 24, 19422,309,280 Stansbury Jan. 26, 1943 2,375,413 Guenther May 8, 19452,390,981 Binens Dec. 18, 1945

